A large plume of smoke from a massive fire is seen in Sun Prairie, Wis., Tuesday, July 10, 2018. Witnesses said the fire broke out after a loud boom Tuesday night shook the community. Police blocked off downtown streets from traffic and onlookers. (AP Photo/Todd Richmond)

Firefighters work the scene of an explosion in downtown Sun Prairie, Wis., Tuesday, July 10, 2018. The explosion rocked the downtown area of Sun Prairie, a suburb of Madison, after a contractor struck a natural gas main Monday, sending an unknown number of people to hospitals, authorities said. (Amber Arnold/Wisconsin State Journal via AP)

Residents are relocated from a nearby home after an explosion in downtown Sun Prairie, Wis., Tuesday, July 10, 2018. The explosion rocked the downtown area of Sun Prairie, a suburb of Madison, after a contractor struck a natural gas main Monday, sending an unknown number of people to hospitals, authorities said. (Amber Arnold/Wisconsin State Journal via AP)

A large swath of downtown Sun Prairie remains closed Wednesday morning, July 11, 2018 in the wake of a gas leak explosion Tuesday evening that leveled a downtown Sun Prairie bar, caused a massive fire at a pizza restaurant, killed a firefighter and and injured more than a dozen other people. Firefighters remained on the scene. (Steve Apps/Wisconsin State Journal via AP)

Smoke rises as firefighters work the scene of an explosion in downtown Sun Prairie, Wis., Tuesday, July 10, 2018. The explosion rocked the downtown area of Sun Prairie, a suburb of Madison, after a contractor struck a natural gas main Monday, sending an unknown number of people to hospitals, authorities said. (Amber Arnold/Wisconsin State Journal via AP)

Authorities work the scene of an explosion in downtown Sun Prairie, Wis., Tuesday, July 10, 2018. The explosion rocked the downtown area of Sun Prairie, a suburb of Madison, after a contractor struck a natural gas main Monday, sending an unknown number of people to hospitals, authorities said. (Amber Arnold/Wisconsin State Journal via AP)

People evacuate as they were told to move farther away the scene of an explosion in downtown Sun Prairie, Wis., Tuesday, July 10, 2018. The explosion rocked the downtown area of Sun Prairie, a suburb of Madison, after a contractor struck a natural gas main Monday, sending an unknown number of people to hospitals, authorities said. (Amber Arnold/Wisconsin State Journal via AP)

In a view looking northwest from above, the aftermath of a gas explosion in downtown Sun Prairie, Wis., is seen Wednesday, July 11, 2018. At the top right of the image is the site of the former Barr House where the explosion originated and leveled the building. Sun Prairie Fire Department Capt. Cory Barr was killed Tuesday when a natural gas explosion leveled most of a city block, including the tavern Barr owned. (John Hart/Wisconsin State Journal via AP)

MADISON, Wis. (AP) — A communications company said Thursday that a subcontractor was working "on site" before an explosion that killed a Wisconsin firefighter this week.

Authorities have said a crew punctured a natural gas main in downtown Sun Prairie on Tuesday, resulting in an explosion that damaged five buildings and killed Sun Prairie Fire Department Capt. Cory Barr.

Verizon Wireless said Thursday it had contracted with Lawrence, Kansas-based Bear Communications for a fiber optics project in Sun Prairie. Bear said in a statement that its subcontractor was working "on site" but gave no other details. Bear spokesman Scott Stein said in a telephone interview that the subcontractor's employees were working in the "vicinity" of the explosion and were evacuated before the blast occurred. He declined to comment further.

Two days after the blast, it remained unclear who was responsible for puncturing the main.

Sun Prairie officials declined to release any information Thursday about the identity of the workers who punctured the main, citing an ongoing investigation.

Bear said in its statement that "many questions" remain and it's cooperating with investigators. TDS Telecom said it has been working on a fiber optics project in Sun Prairie but none of their workers or contractors ruptured the line.

Amy Jahns is a spokeswoman for We Energies, which owns the gas main. She declined to comment Thursday when asked if whoever punctured the line had made any effort to locate it before starting work, referring questions back to police.

The explosion happened after police received a call of a gas leak in downtown Sun Prairie, a Madison suburb of about 30,000 people. Something sparked the gas while firefighters and other emergency responders were evacuating people from the area.

The blast rained debris up and down the street and leveled the Barr House, a tavern Barr owned. Ensuing fires damaged four other buildings, including Glass Nickel Pizza and a steak restaurant.

Barr was working to evacuate people when he was caught in the blast, Fire Chief Chris Garrison has said. Eleven other people, including five other firefighters and a police officer, were hurt.

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Follow Todd Richmond on Twitter at https://twitter.com/trichmond1

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This story has been corrected to reflect that the explosion was two days ago, not three.